I didn't realise "radar detectors" were still a thing? After the commercial utilisation of GPS, most "radar detectors" / speed camera location alerts, made use of a GPS Database file you'd download to your device.
Then instead of active radar detection, they alert you to a known camera location (or other type of hazard) via the GPS database, based on the recorded known cameras in that area (you are driving through).

Some modern variations of "speed cameras" use digital technology and don't emit any type of radar. Using photography / ANPR instead!